516.900.201

The Simplex 516.900.201 is the detector head for the 721P conventional UL-listed optical (photoelectric) smoke detector, designed for 2-wire conventional fire alarm systems with self-monitoring and contamination compensation features.
It provides 450-900 sq ft coverage depending on ceiling type and air flow conditions, featuring dust/dirt compensation to prevent false alarms and extend service life, with test compatibility using smoke generators or magnetic test tools.
Key Specifications
Feature
Specification
Type
Optical (photoelectric) smoke sensor head ​
Coverage
450-900 sq ft (42-84 sq m); 30 ft spacing smooth ceilings
Voltage
2-wire conventional (15-33 VDC typical) ​
Compatibility
4B-UL, 5B bases; 2004/2008/4007 series panels
Temperature
32°F to 100°F (0°C to 38°C) ​
Features
Self-monitoring, contamination compensation